Web tension equalizing device



Fatented ov. 3%, i9

Guy 3.

End i 1&1 New J rey F t- TENSION EQUALIZING DEVIGE Crocker, NewBrunswick, N. 3., assor to Tape Corporation, a corporation ofApplication July 21,1945, Seriai No. coasts (This invention relates toapparatus for controlling the tensionof webs, for example paper, in thecourse of unwinding the web from a roll or winding it onto a roll. a

It is well known that flexible webs, such as paper, are dificult to windand unwind uniformly and to keep straight and flat because thevariations in the thickness, elasticity and other characteristics of theweb causes the tension in the web to vary from time to time across thewidth of the web. This may cause the web to run crooked, wrinkle, bunch,sag, or tear unless some means is provided to keep the web under uniformtension across its width by counteracting the efiects of the variations.Numerous devices have been proposed for keeping the web under uniformtension, but those which have come to my attention are expensive orcomplicated to build and maintain or do not satisfactorily control thetension of the web.

It is one of the objects of my invention to provide an improved, simpleand economical means for maintaining uniform tension across the width ofa web being wound or unwound, or being passed through any desiredmachine for processing.

In the accompanying drawings,

Fig. i is a diagrammatic view in perspective of a portion of a webtreating machine embodying my invention,

Fig. 2 is a section on the plane determined by the lines 2-2a, lookingin the direction of the arrow, showing the parts in the positionindicated in Fig. i, and

Fig. 3 is a corresponding section showing the parts in a difierentposition.

Referring to the drawings, iii designates a web, for example of paper,which is being unwound connected to the pivots by two oflset arms atarfrom a supply roll i2 and is wound on a take-up roll it after beingprocessed, as by being coated by a spreading knife it disposed between apair of supporting rollers it. The take-up roll moves the web in thedirection of the arrow in Fig. 1. After being coated at the spreadingknife, the web is passed through any suitable drier, oven, or otherdesired processing apparatus it. The roll i2 is braked by any suitableform of brake, not shown, to prevent the web from unwinding too fast andto preserve the desired ten sion in the web.

In order to preserve a uniform tension across the width of the web, inspite of the tendency to vary the tension of increments across the widthof the web, I provide a tension bar it of the form shown in Figs. 2 and3 between the supply roll it and the first supporting roll it. As showna Ciao. (c1. arr-2.1)

best in Fig. 3, the bar has a pair of aligned pivots it supported in anysuitable fixed bearings 22 on the machine frame 23. The portion of thebar between the pivots is of z-form; that is, it includes a centralstraight sloping portion 2% ranged at 180 to each other. The center itof the straight central portion it lies on the axis til-30 of the pivots2b. This axis is placed so that it will always be above the varyingupper surface of the roll it from which the paper is unwound, thesurface being represented by the dotted line it.

men operation is started, the tension bar is placed as shown in Figs. 1and 2, so that the portion between the pivots .lies in a horizontalplane and the paper is fed across the bar and through the machine. Aslong as the paper remains uniform and straight and the tension of thetwo edges of the web is the same, the bar remains in the position shownin Fig. 2 and the paper drags across it; However, just as soon as thetension on one side of the paper, for example the left, shown in Fig. 3,becomes less than the tension on the other side of the web, the

.high tension side pushes down its end than? central portion 243,rotating the bar from the fiat position shown in Fig. 2 to some slopingposition asindicated in Fig. 3. The bar is rotated by the web until therising and i'ailingends oi the sloping portion to equalize the tensionbetween the sides oi the web. It the difierence between the tension onthe sides increases the bar is rotated still further, its maximumposition of correction being shown in Fig. 3 with the arms 2i? at rightangles to the line of travel of the web. An decrease in the differenceof tension between. the two sides automatically moves the bartoward thefiat position until the tension again becomes equal.

n will be noted that the centerat or? the bar remains in the axis ofrotation, the bar in effect having two arms 2E and 250 whichsimultaneously move toward and away from the web as the diiierence intension varies.

The bar may be made of any suitable material, for example hardened andpolished steel, or glass. The bearings 22 are of any mourn suitable typewhich will reduce friction to a minimum. The entirearrangement is simpleand inexpensive and operates automatically without any attention on thepart of an operator to preserve uniform tension across the width of theweb.

While the device has been illustrated as applied to a web moving in ahorizontal plane, it

is equally adaptable to webs moving in a vertical plane or in anydesired direction, the rod being balanced in its bearings and notdependent upon gravity but being operated solely by the pressure of thepaper in contact with the rod.

I claim as my invention:

1. Tension control apparatus comprising in combination means-for movinga web in the direction of its length and an elongated tension regulatingmember pivoted on an axis transverse to the length of the web andparallel to the normal plane of the web and adapted to contact the webalong the length of the member, an intermediate point of said memberbeing in the axis of the member and the member having a portion on oneside of said point adapted to move in the direction toward the web whentension on one side of the web decreases, and havinga portion on theother side of said point adapted simultaneously to move in the directionaway from the web.

2. Tension control apparatus comprising in combination means for movinga. web in the direction of its length and a tension regulating baradapted to extend across the web and pivoted for rotation on an axistransverse to the length of the web and parallel to the normal plane ofthe web, the bar having a portion between the pivots .adapted to contactthe web along the length of said portion, said portion being inclined tothe axis and extending on opposite sides of the axis.

3. Tension control. apparatus comprising in combination means for movinga web in the direction of its length and a tension bar adapted tocontact the web across the width of the web and pivoted on an axisparallel to the normal plane of the Web, the bar being rotatable on itsaxis in response to variation or tension on opposite edges of the web,the portion of the bar in contact with the web being inclined to thepivot axis whereby rotation of the bar about its axis by the webinclines said portion of the bar to the normal plane of the web.

4. Tension control apparatus comprising in combination means for movinga web in the direction of its length and a tension bar adapted tocontact the web across the width of the web and pivoted on an axisparallel to the normal plane of the web, the bar being rotatable on itsaxis in response to variation of tension on opposite edges of the web,the portion of the bar in contact with the web being inclined to thepivot axis and extending on opposite sides of the axis whereby rotationof the bar about its axis by the web inclines said portion with respectto the normal plane of the web.

5. Tension control apparatus comprising in combination means for movinga web in the direction of its length and a tension bar adapted tocontact the web across the width of the web and pivoted on a fixed axisparallel to the normal plane of the web, the bar being rotatable on itsaxis in response to variation of tension on oppo-v site edges of theweb, the portion of the bar in contact with the web being inclined tothe pivot axis whereby rotation of the bar about its axis by the webinclines said portion with respect to the normal plane of the web.

6. Tension control apparatus aomprlsing in combination means for movinga web int e direction of its length and a tension bar ad pted to contactthe web across the width of the eb and pivoted on an axis disposedacross the web, the bar being rotatable on its axis in response tovariation of tension on opposite edges of the web, the portion of thebar midway between the edges of the web coinciding with the axis of thebar and the portion of the bar contacting the web being inclined inopposite directions from the axis whereby rotation of the bar about itsaxis inclines said last mentioned portion with respect to the normalplane of the web.

7. Tension control apparatus comprising in combination means for movinga web in the direction of its length and a tension bar adapted tocontact the web across the width of the web and pivoted on an axisdisposed across the web, the bar being rotatable on its axis in responseto V variation of tension on opposite edges of the web,

the portion of the bar midway between the edges of the web coincidingwith the axis of the bar,

the portion of the bar adapted to contact the web on one side of saidmidway point being inclined to the axis in the direction of motion ofthe web and the contacting portion on the opposite side of said midwaypoint being inclined to the axis away from the direction of motion ofthe web.

8. Tension control apparatus for webs comprising in combination meansfor moving a web in the direction of its length, a Z-s'naped bardisposed in a plane and adapted to contact the web across the width ofthe web, the bar being pivoted on a longitudinal axis for rotation withvariations in the tension of the opposite edges of the web, the portionof the bar on one side of the center of the web being inclined to theaxis in the direction of travel of the web and the portion of the bar onthe other side of the center of the web being inclined to the axisopposite to the direction of travel of the web whereby rotation of thebar will move the bar toward the normal plane of the web on one side ofthe center of the web and away from the normal plane of the web on'theother side of the center of the web.

GUY J. CROCKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Date

